I think most of the important stuff on the Internet has been built. There will be continued innovation, for sure, but the great problems of the Internet have essentially been solved.

The first step is to establish that something is possible; then probability will occur.

The revolutionary breakthrough will come with rockets that are fully and rapidly reusable. We will never conquer Mars unless we do that. It'll be too expensive. The American colonies would never have been pioneered if the ships that crossed the ocean hadn't been reusable.

It was obvious to me that we could never colonize Mars without reusability, any more than America would have been colonized if they had to burn the ships after every trip.

Many things are improbable, only a few are impossible.

Land on Mars, a round-trip ticket - half a million dollars. It can be done.

I feel very strongly that SpaceX would not have been able to get started, nor would we have made the progress that we have, without the help of NASA.